When you know the title of the item you are seeking, the first step is to search by title in an online catalog.
In the BGSU Libraries Catalog, the OhioLINK Central Catalog, and WorldCat, books that have been assigned subjects with the subheadings in the list below might be primary sources. However, don’t expect that a book that includes primary sources will always include one of these words or phrases in a subject heading. Also, these subheadings are not used in other databases.
Anti-Nazi Movement -- Germany -- Berlin -- Biography
Edelweisspiraten (Resistance Groups) -- Biography
Anti-Nazi Movement -- Personal Narratives
Holocaust, Jewish (1939-1945) -- France -- Le Chambon-sur-Lignon -- Personal Narratives
Holocaust, Jewish (1939-1945) -- Personal Narratives
Jewish Children in the Holocaust -- Biography
Scholl, Hans, 1918-1943 -- Correspondence
World War, 1939-1945 -- Jews -- Rescue -- Sources
World War, 1939-1945 -- Underground Movements -- Norway -- Biography
For information about the difference between primary and secondary sources, see:
Don't forget that Google Books and the Internet Archive both include the full text books that are no longer under copyright. To be sure and retrieve only full text books from Google Books, check "Full view only" on the search page. The Internet Archive also includes audio and video files.
Don't expect to find a great deal of full text resources here because most of the books written during World War II are still under copyright. However, it can be used as a place to identify materials that you can then borrow from a library.
A sample of titles that might be useful: